The objective of this application is to understand the role of protein phosphatase 5 (PP5) in GR signaling as a molecular chaperone and in regulating signal transduction by steroid receptors and other molecules. Specifically, Aim 1 will define at what point of the GR signaling pathway PP5 is required; Aim 2 will test whether PP5 regulates the phosphorylation state of the GR and other proteins in the GR heterocomplex; Aim 3 will test whether PP5 has a general function as a molecular chaperone of other proteins associated with hsp90.